Date: Mon, 02 Nov 2020 23:31:56 +0000 From: bugzilla-noreply@freebsd.org To: virtualization@FreeBSD.org Subject: [Bug 250802] bhyve exited with status 134 when GPU PCI passthrough Message-ID: <bug-250802-27103-xvlIMpIF8l@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-250802-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-250802-27103@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D250802 Robert Crowston <crowston@protonmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |crowston@protonmail.com --- Comment #2 from Robert Crowston <crowston@protonmail.com> --- Are you on AMD? I have had the same problem. For some reason the processor is unable to handle accesses to BARs mapped a= bove 4 GB. The vm exits on such access and transfers control back to the vmm. B= ut the vmm does not expect to handle memory passthrough -- the processor is supposed to handle that natively -- only i/o passthrough, tripping this assertion. There is a hardcoded limit where we decide whether to allocate a bar above = or below the 4 GB mark, in pci_emul.c, at pci_emul_alloc_pbar(): /* * XXX * Some drivers do not work well if the 64-bit BAR is allocated * above 4GB. Allow for this by allocating small requests under * 4GB unless then allocation size is larger than some arbitrary * number (32MB currently). */ if (size > 32 * 1024 * 1024) { In the past I have found that by raising this limit, such that all bars are allocated in the lower 32 bit address space, I can start a GPU under Linux.= I have not had success under Windows. It's worth noting that most real BIOS or UEFIs preferentially allocate even large BARs in the lower 4 GB of the address space, so that configuration is much better tested for consumer devices. -- RHC. --=20 You are receiving this mail because: You are the assignee for the bug.=
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